<\/p>\n
I just sent a note off to Will Shortz about an error in the NY Times crossword puzzle.\u00a0 Here’s what I said.<\/p>\n
Pretty much every time that I think I've noticed an error in the Times crossword, the error turns out to be mine.\u00a0 But as a physicist and physics teacher, I'm confident about this one.\u00a0 In Saturday's puzzle, 59 down is defined as "Energy expressed in volts: Abbr.", and the answer is "EMF".\u00a0 This definition is incorrect.\u00a0 An EMF is generally expressed in volts, but it's not an energy.\u00a0 In fact, the volt isn't even a unit of energy, so "energy expressed in volts" is sort of like "distance expressed in pounds" or "speed expressed in dollars."<\/p>\n
EMF is a form of voltage, or equivalently of electric potential (these two are synonyms).\u00a0 Another way to say it is "energy per charge", but that "per charge" part is very important.\u00a0 For instance, a car battery supplies an emf of 12 V, which is less than the emf of a pair of 9-volt batteries.\u00a0 But despite the relatively small emf, the car battery has a lot more energy stored in it than the two 9-volts.<\/p>\n
By the way, you probably don't remember me, but we spoke on the phone about 10 years ago: I was an on-air participant in the NPR puzzle.\u00a0 You stumped me with "Pal Joey", but other than that I did OK.<\/p><\/blockquote>\n
By the way, emf is a good candidate for the most misleading name in physics: the F stands for “force”, but in addition to not being an energy, emf isn’t a force either.\u00a0 At least one textbook (I can’t remember which) says that you shouldn’t think of EMF as standing for anything, putting it in the same category as\u00a0 KFC and the AARP.\u00a0 (The Oakland A’s used to be in this category too, but I think they’re not anymore.)<\/p>\n","protected":false},"excerpt":{"rendered":"
I just sent a note off to Will Shortz about an error in the NY Times crossword puzzle.\u00a0 Here’s what I said. Pretty much every time that I think I've noticed an error in the Times crossword, the error turns out to be mine.\u00a0 But as a physicist and physics teacher, I'm confident about this … Continue reading Vengeance is mine<\/span><\/a><\/p>\n","protected":false},"author":12,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-90","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/blog.richmond.edu\/physicsbunn\/wp-json\/wp\/v2\/posts\/90","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.richmond.edu\/physicsbunn\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.richmond.edu\/physicsbunn\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.richmond.edu\/physicsbunn\/wp-json\/wp\/v2\/users\/12"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.richmond.edu\/physicsbunn\/wp-json\/wp\/v2\/comments?post=90"}],"version-history":[{"count":0,"href":"https:\/\/blog.richmond.edu\/physicsbunn\/wp-json\/wp\/v2\/posts\/90\/revisions"}],"wp:attachment":[{"href":"https:\/\/blog.richmond.edu\/physicsbunn\/wp-json\/wp\/v2\/media?parent=90"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.richmond.edu\/physicsbunn\/wp-json\/wp\/v2\/categories?post=90"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.richmond.edu\/physicsbunn\/wp-json\/wp\/v2\/tags?post=90"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}